Usage of heavy metal-free compounds in surface coatings

Abstract

Coatings have been used since time immemorial for decorative and protective purposes. During the initial periods, when not much information was available regarding the health impact of the raw materials, there was no thought given or restrictions put on use of any ingredients in coatings. Some of the raw materials like white lead (lead carbonate), red lead (lead oxide), hexavalent chromium compounds, and other similar compounds were being used in large quantities to get specific paint film properties. This not only affected human health but also with no effective effluent treatment contaminated soil and water resources. With progress in technology and diagnostics, lead and chromium compounds have been identified as carcinogens. The developed countries (Europe and USA) were the first to ban the use of lead in their products in the 1970s and 1980s, but due to mainly economic reasons, these are still being used in the developing countries. As the long-term health impact is too much to bear, regulations/legislations have been enacted by the governments restricting use of lead/chrome in paints. The Global Alliance to Eliminate Lead Paint (GAELP), a joint association formed under the United Nations Environment programme, and World Health Organization have agreed to phase out manufacture and sale of paints containing lead by 2020. Similar restrictions exist for many other compounds used in coatings. The article attempts to present a synopsis of the history of coatings composition, impact of the heavy metals on health and environment, and the options available for shifting to safer coating composition. As major focus of the world is on lead elimination, it has been covered in more detail, but the article also provides information on other metals, namely cadmium, chromium, mercury, arsenic, antimony, tin, nickel, manganese, cobalt, etc., and their current status.